In making a diagnosis of arterial sclerosis using an ultrasonic diagnostic apparatus, the intima-media complex thickness (which will be abbreviated herein as “IMT”) of a carotid artery is known as one of most important indices to the status of an initial atherosclerosis. The IMT means the thickness of an intima-media complex in the vascular wall of a carotid artery. As shown in FIG. 18, the intima-media complex is a layer that is visible between the vascular lumen and the adventitia. And when making an inspection, the boundary between the vascular lumen and the intima (which will be referred to herein as a “lumen-intima boundary”) and the boundary between the media and the adventitia (which will be referred to herein as a “media-adventitia boundary”) are detected and the thickness between them is measured. A method for automatically measuring the IMT is disclosed in Patent Document No. 1, for example.
In general, when the IMT is measured, an IMT measuring range is set along the carotid artery and the maximum thickness (max IMT) or mean thickness (mean IMT) is measured within that range as shown in FIG. 18. For example, Non-Patent Document No. 1 recommends that such an IMT measuring range have a length of 1 cm.